The invention relates to a mixing valve for mixing two flows and intended more particularly for the sanitary field, for mixing hot water and cold water. The invention relates more particularly to the field of valves of a particular type in which the elements providing the mixing are ceramic plates with polished contacting surfaces and movable with respect to each other.
So called mixing valves, with ceramic plates (sintered alumina oxide) also called "mirrors" because of their smooth surfaces in mutual contact, are more and more appreciated in the field of sanitary ware. The ceramic plates very often comprise duct elements communicating from one plate to another so that the flow section of the two fluids is made adjustable before mixing thereof properly speaking, by positioning the two plates. Known systems very generally have a fixed ceramic plate and a movable ceramic plate, whose position may be varied by means of a single control in the form of a lever, movable in two directions corresponding respectively, for the user, to adjustment of the mixed water flow rate and to the adjustment of the ratio of the two fluid flows in said mixture.
Up to now, all the systems proposed are such that the arc for adjusting the mixture described at full flow of mixed water is less than that which is described at low flow rates. Consequently, the operating forces required and the sensitivity of adjustment are not constant depending on the position of the flow rate lever. The modification of one of the adjustments is reflected to a greater or lesser degree on the other.
A first object of the invention is to provide a valve with polished plates, actuated by a single lever and the two adjustments of which are really independent.
Furthermore, known devices are provided with plates pierced so that, for the most part, the two flows of cold and hot water pass through the fixed plate, are mixed at the level of the movable plate without passing therethrough and so that this mixture is discharged towards an outlet substantially parallel to the two inlets, generally through an additional orifice in the fixed plate. This path of the water through the valve and particularly the complete change of direction which occurs between the fixed and movable plates is very generally the cause of relatively troublesome operating noises, so that numerous valves of this kind are provided with an antinoise strainer which moreover has the major drawback of becoming very rapidly clogged up. Another aim of the invention is to propose a device with a low operating noise level, without strainer, particularly because of the fact that the mixed water may be discharged laterally along the contour of the movable plate, which comprises no duct element, the characteristics of the two adjustments respectively of the flow rate and of the mixture being obtained by the very shape of said contour.